In yards and gardens at home and in other locations, a common problem is the encroachment of grass and weeds into undesired areas such as around the base of young trees, in a landscaped section, or even onto sidewalks and paths. A common approach is to provide a lawn edging to create a barrier restricting the direct growth into such protected areas. Traditional forms of lawn edging have included basic planar sheets or strips of plastic, tin, or other materials held in place by stakes driven into the ground. These stakes sometimes are provided with hooks to restrain the movement of the sheets and sometimes are passed through an eye or other opening to restrict sheet movement. In either event the edging provides a physical barrier starting at ground level and rising up to the top of the barrier strip.
Another alternative is to use a heavier and bulkier barrier to restrict incursion into the protected areas. The most traditional example would be the use of bricks resting on the ground as a border. Other examples would include the Landscape Edging of U.S. Pat. No. 4,747,231 of LeMay et al which consists of a series of log sections strung together on a strip or the Decorative Lawn Edging of U.S. Design Pat. No. 361,853 which provides the appearance of a set of trimmed two by four tops strung together along a strip. The Plastic Landscape Edging Unit of U.S. Design Pat. No. 276,494 to Novak also provides log shapes strung on a strip (or integrally molded with a strip), but also apparently provides apertures for receiving some type of stake already in the ground. In any event, these examples also provide some protection against incursion while additionally creating a decorative effect. They are not well suited for hammering a significant distance into the ground, however, nor do they provide the stability of a deeper connection with the ground.
The prior art also contains fence units such as U.S. Design Pat. No. 359,130 to Northrop et al and U.S. Pat. No. 3,701,477 to Matt et al (which is primarily intended as a sprinkler system) which may also be placed to serve as a border around protective areas. While these devices consist of a sequence of posts with a set of cross beams, they are not as well suited for actually preventing the incursion of grass or weeds and form more of a visual border than an actual barrier. The sprinkler concealing fence of Matt et al does not even have contact at ground level by its cross beam, leaving the space between the posts completely open. The fence unit of Northrop does not appear to be intended to provide complete protection against incursion. The fence units also have the problem that although they are designed to be have at least the "posts" inserted into the ground they are not well configured for hammering to accomplish this goal. In Matt et al the posts actually come to a point, while on the Northrop fence unit the top surface of the posts provides a rather thin rectangle.
Finally, U.S. Pat. No. 2,877,600 to Slate for fence construction and U.S. Pat. No. 5,456,045 to Bradley et al for lawn edging strip provide solid walls which are inserted to some depth within the ground to act as borders. Slate still does not provide much in the way of a surface for hammering and also provides extensions intended to rest on the surface of the ground to prevent the unit from being inserted too far into the ground. Bradley et al appears to be the most flexible, providing a top surface which although scalloped provides a broad surface for hammering the strip into the ground. Bradley also provides tapered ribs and a tapered bottom edge to facilitate insertion. Bradley loses, however, the advantages of deeper penetration providing more stability with less material provided by stakes which go to a greater depth than the main body of the strip, as well as the more traditional look provided by such stakes.
Further, a problem also exists when the ground freezes and contracts resulting in "frost-heave" by which a strip inserted into the ground may be forced out of the ground. Neither Bradley nor Slate provide any mechanism for retarding the motion of the strip back out of the ground in such a circumstance. Further Bradley's full body taper might actually facilitate such undesired motion in response to ground contraction, while Slate actually calls for extensions on top of the surface to prevent the strip from going too deep. Additionally, neither Slate nor Bradley provide an uninterrupted surface for providing additional decoration to enhance the appearance of the strip. In this manner they carry many of the same weaknesses of the original planar strips which provided an unattractive functional means to discourage incursion into protected areas, but did not have the flexibility in appearance to create an appealing visual border as well. Bradley in fact has tapered support strips running from bottom to top throughout its length, with only its scalloped top surface generating any visual appeal for the border outside of the immediate function of discouraging incursion.